Cholis is a large rock planet wreathed in a haze of carbon dioxide and xenon. It was discovered by batarian astronomers during the last century and first visited in the 2150s by Hegemony survey teams. A small number of colonists lived in aerostat habitats above its oppressive cloud layer, harvesting carbon dioxide. No habitats can be detected now--it is likely the Reapers eliminated them or the colonists submerged into the scorching atmosphere in an attempt to hide.